Process for preparing polyhydric



'United States Patent PROCESS FOR PREPARING POLYHYDRIC ALCOHOLS FROM HEXITES Fritz Conradin, Tamins, Graubunden, Giuseppe Bertossa, Domat (Ems), Graubunden, and Johann Giesen, Haldenstein, near Chur, Switzerland, assignors to Iuventa A. G. fuer Forschung und Patentverwertung, Zurich, Switzerland No Drawing. Application April 4, 1957 Serial No.-650,558

polyhydric alcohols from hexites by hydrogenation cleavage in the presence of catalysts at elevated pressure and temperature.

It is known to apply hydrogenation cleavage to hexites, obtained by reduction of hexoses, whereby polyhdric alcohols having less than, 6 carbon atoms are obtained. (See'Swiss patent application, Ser. No. 32,061, of April 12, 1956.) Cleavage products obtained are e. g. ethylene glycol, 1,3- or 1,2-propylene glycol, glycerine, and en'thrite. The percentages of the cleavage products obtained vary widely in the processes practiced up to now.

It has nowybeen found that thehydrogenation cleavage of hexites in the presence of catalysts, performed at elevated-pressure and temperature, may be carried out with controlled production ofany one of the cleavage products or a plurality of thesame. Depending on which one of the cleavage products is preferred, the hydrogenation cleavage is effected in the presence of catalysts which eontainelements of the group of-nickel, copper, cobalt, chromium or silver. The temperature during the cleavage is maintained above 180" C. and pressure amounts to more than 10 atmospheres.

According to theinvention, the cleavage of the hexites is carried out in approximately neutral aqueous solution. When it is desired to produce preferentially 1,3- propylene glycol, the cleavage is carried out with hydrogen pressure of 100-200 atm., preferably 140-160 atm., and temperatures from 190-220 C., in the presence of catalysts containing nickel in combination with copper and/or cobalt. The copper content in this case is about 124%, the nickel content also 124%. When it is intended to use a catalyst containing cobalt in addition to copper, the composition may be as follows: Nickel 10-14%, cobalt 10-14%, copper l-%. The metals are precipitated as hydroxides, or, together with the carrier, e. g. magnesium hydroxide, as mixed hydroxides. The precipitate'is'shaped as desired, in a conventional manner, dried, and reduced. Instead of the above named'mix'ed catalysts, copper chromite may be used, which is preferably activated with silver. The yield in 1,3-propylene glycol can be increased up to 70%.

When, however, the output in 1,2-propylene glycol is to be increased, catalysts'are used which containacarn'er, e. g. magnesiurn'oxide, and thereon about 25% copper and about 20-25% nickel. The pressure is about 50atm., preferably 20-30 atm., the temperatures 180- 210 C. The yield in 1,2-propylene glycol can be increased toabout 30% by this modification of the process.

Fee

For preferred formation of glycerine and ethylene glycol, catalysts are used, according to the invention, which contain, only cobalt and nickel in addition to a carrier, e. g. alkaline earth oxides, such as magnesium oxide. The content in cobalt is 1-24%, and the content of nickel likewise 1-24%. "The temperature is preferably maintained between 200 and 220 C., the hydrogen pressure between and 200 atm., preferably from 160 atm. Catalysts of cobalt and nickel on magnesium oxide as carrier can be prepared in a simple manner by precipitating the metals as oxalates by means of oxalic acid from an aqueous solution containing salts of cobalt, nickel and-magnesium; the precipitate'is washed and dried and -t'hen--reduced in aknown manner, e. g. by

, tinuous.

*The process according to the invention will .now be .more fully described in a number of examples, but '-it should be. understood that .these' are given by. .way. of

illustration andnotvof limitation and that many changes in the details can be made without'departingjfrom the spirit of the invention.

Example 1 To 500 cc. of a- 1'0'%. aqueous sorbite solution, 25 grams-of a catalyst areradded which consists of 12.4% nickel, 12.4% copper, and 75% magnesium oxide; the mixture is placed in an autoclavelprovidedwith a stirrer and treated with hydrogen under a pressure of atm. at a temperature of 210 C. for 10 hours. After expansion, the contents of the autoclave are; subjected .to distillation, water being first drivenpfi at normal pressure. The alcohols are then obtained byfractional'distillation. The residue contains 8% of the sorbite used initially, the conversion is therefore. 92%'. The fractions of the distillate consist of 53% LS-propylene glycol, 18% 1,2-propylene glycol, 25% .glycerine andno glycol. The remaining 4% consist partly of er'ithrite. (The values are given percent by, weight of the sorbite converted during the reaction in this and all the following examples.)

-Examples 2 The same amount of 10%aqueoussorbitesolution-as used -inExample 1,.is hydrogenated under-the following conditions: The catalyst used is 3% copper,.22% nickel, and 75% magnesiumoxide. Reaction temperature 220 C., pressure 150 atm., reaction time Sjhours. Theproducts are worked up as ,described above; 40% vof the sorbite initially used are recovered without change so that conversion amounts. to 60%.. The distillates obtained are 40% '1,3'-propylene glycol, 12% 1,2-propylene glycol, and 15% glycol, and 30% glycerine. The remainder i. e. 3%, contains some erithrite.

Example "3 500 cc. of.a.l0% aqueous sorbite solution arehydrogenated and subsequently worked .up by; disti lation as described in Example 1. Reaction temperature 195 C., pressure 150 atm., reaction time 20 hours.

Catalyst: 12% nickel, 12% cobalt, 1% copper, and 75% magnesium oxide.

55% of unreacted sorbite are obtained. The conversion is therefore 45%.

The distillates contain: 44% 1,3-propylene glycol, 11% 1,2-propy1ene glycol, 39% glycerine, and no ethylene glycol. The residue of 6% still contains erithrite.

Example 4 In an autoclave provided with a stirrer, 25 grams of a copper chromite catalyst activated with silver, are added to 500 cc. of a 10% neutral aqueous sorbite solution; (pH=6-8). In the autoclave a hydrogen pressure of 150 atmospheres at a temperature of 200 C. is maintained for 20 hours.

After expansion and after the autoclave has cooled down, the content is fractionally distilled, water being first eliminated at normal pressure. The distillation is then continued at reduced pressure, whereby the polyhydric alcohols are obtained. In the residue, 34% of the used sorbite remain together with the catalyst. The conversion is therefore 66%. The distillates contain: 61% 1,3-propylene glycol, 10% 1,2-propylene glycol, 6% ethylene glycol, and 20% ,glycerine. The remainder consists partly of erithrite.

Example 5 The same amount of aqueous sorbite solution and the same catalyst are used as in Example 4, with the following conditions:

Temperature 200 0., pressure 150 atm., reaction time hours. Work-up as in Example 4. 42% of the sorbite used are unreacted. The conversion is therefore 58%. The yields calculated on the conversion are 60% 1,3- propylene glycol, 8% 1,2-propylene glycol, 7% ethylene glycol, and 23% glycerine. The remaining 2% contain some erithrite.

Example 6 To 500 cc. of 10% sorbite solution (pH=7.5) in an autoclave with stirrer, are added 25 grams of a catalyst consisting of 2% copper, 23% nickel, and 75% magnesium oxide. Hydrogenation takes place at a temperature of 210 C. and a hydrogen pressure of 25 atm. during 10 hours.

After expansion and after the autoclave has cooled down, the contents are distilled for driving off water and are then fractionally distilled at reduced pressure. The distillation residue contains in addition to the catalyst 17% unreacted sorbite. The conversion is therefore 83%. The distillation fiactions contain 32% 1,2-propylene glycol, 20% 1,3-propylene glycol, 10% glycol, and 19% glycerine. The remaining 19% contain still some erithrite.

Example 7 500 cc. of a 10% sorbite solution are hydrogenated as in Example 6. Reaction conditions: Temperature 220 C., pressure 25 atm., reaction time 5 hours, 25 grams catalyst of the same composition as in Example 6. The Work-up of the reaction products results in 21% unreacted sorbite in the residue (conversion 79%) and 27% 1,2-propylene glycol, 30% 1,3-propylene glycol, 19% glycol and 18% glycerine in the distillates.

This example shows that upon raising the temperature to 220 C., the yield in 1,3-propylene glycol is considerably increased.

Example 8 500 cc. of a 10% sorbite solution are hydrogenated as described in Examples 6 and 7, with the following conditions: Temperature 210 C., pressure 25 atm., reaction time 10 hours, 25 grams of catalyst consisting of 4 3% copper, 22% nickel, and 75% magnesium oxide. 16% of unreacted sorbite are obtained, the conversion is therefore 84%.

The fractional distillation yields 27% 1,2-propylene glycol, 21% 1,3-propylene glycol, 18% glycol, and 15% glycerine.

Example 9 In an autoclave provided with a stirrer, 500 cc. of a 10% sorbite solution are mixed with 25 grams of a catalyst consisting of 20% cobalt, 5% nickel, and 75 magnesium oxide. Hydrogenation is carriedon for 10 hours at a temperature of 210 C. and a hydrogen pressure of atm.

After expansion and after the autoclave has cooled down, the content is distilled, water being first driven off at normal pressure, and the mixture being then fractionally distilled at reduced pressure. The residue contains in addition to the catalyst 7% unreacted sorbite. The conversion is therefore 93%. The distillates contain 34% glycerine, 31% glycol, 11% 1,2- and 19% 1,3-propylene glycol. The remaining 5% still contain some erithrite.

Example 10 500 cc. of a 10% aqueous sorbite solution are hydrogenated as described in Example 9, but under the following conditions:

Temperature 210 (3., pressure 150 atm., reaction time 10 hours, 25 grams catalyst consisting of 5% cobalt, 20% nickel, and 75% magnesium oxide. The work-up as in Example 9; the yield is: 4% unreacted sorbite (conversion 96%), 34% glycerine, 32% glycol, 15% 1,2- and 19% 1,3-propylene glycol.

Example 11 500 cc. of a 10% aqueous sorbite solution are hydrogenated as described in Example-9, but under the following conditions: Temperature2l5 0., pressure 150 atm., reaction time 5 hours, 25 grams catalyst consisting of 12.5 cobalt, 12.5% nickel, and 75% magnesium oxide.

Work-up as in Example 9. 22% of unreacted sorbite are obtained. The conversion is therefore 78%. The reacted sorbite is converted into 36% glycerine, 30% glycol, 16% 1,2-propylene glycol, and 13% 1,3-propylene glycol.

What We claim is:

1. A process for preparing 1,3-propylene glycol and glycerol plus ethylene glycol by hydrogenation cleavage of hexitols in the presence of catalysts at elevated pressures and temperatures, which comprises eflecting the hydrogenation cleavage in the presensce of catalysts selected from the group consisting of mixtures of nickel, copper and cobalt; copper chromite and silver; copper and nickel; cobalt and nickel, at temperatures of 220 C. and at pressures of 100-200 atmospheres; the 1.3 propylene glycol being selectively produced at temperatures between 220 C. and at pressures of 100-200 atmospheres, the catalyst being selected from the group consisting of mixtures of nickel, copper and cobalt; copper chromite and silver; copper and nickel; the glycerol plus ethylene glycol being selectively produced at temperatures between 200 and 220 C., the catalyst being selected from the group consisting of mixtures of cobalt and nickel.

2. The process according to claim 1, wherein the catalyst used in the preparation of glycerol plus ethylene glycol consists of l-24 percent each of nickel and cobalt, the remainder being magnesium oxide on which said nickel and cobalt areprecipi tated.

3. The process according to claim 1, wherein the catalyst used in the preparation of 1,3-propylene glycol consists of 1-24 percent each of nickel and copper, the remainder being magnesium oxide upon which said copper and nickel are precipitated.

4. The process according to claim 1, wherein the catalyst used in the preparation of 1,3-propylene glycol consists of 10-14 percent nickel, 10-14 percent cobalt and 1-5 percent copper, the remainder being magnesium oxide on which said copper, nickel and cobalt are precipitated.

5. The process according to claim 1, wherein the catalyst used for the preparation of 1,3-propylene glycol consists of copper chromite activated by silver.

6 References Cited in the file of this patent UNITED STATES PATENTS 2,004,135 Rothrock June 11, 1935 5 2,335,731 Bottoms Nov. 30, 1943 2,381,316 Stengel et al Aug. 7, 1945 OTHER REFERENCES Ser. No. 295,616, Natta et al. (A. P. C.), published 10 April 20, 1943 (abandoned). 

1. A PROCESS FOR PREPARING 1,3-PROPYLENE GLYCOL AND GLYCEROL PLUS ETHYLENE GLYCOL BY HYDROGENATION CLEAVAGE OF HEXITOLS IN THE PRESENCE OF CATALYSTS AT ELEVATED PRESSURES AND TEMPERATURES, WHICH COMPRISES EFFECTING THE HYDROGENATION CLEVAGE IN THE PRESENCE OF CATALYSIS SELECTED FROM THE GROUP CONSISTING OF MIXTURES OF NICKEL, COPPER AND COBALT; COPPER CHROMITE AND SILVER; COPPER AND NICKEL; COBALT AND NICKEL, AT TEMPERATURES OF 180220*C. AND AT PRESSURES OF 100-200 ATMOSPHERES; THE 1.3 PROPYLENE GLYCOL BEING SELECTIVELY PRODUCED AT TEMPERATURES BETWEEN 190-220*C. AND AT PRESSURES OF 100-200 ATMOSPHERE, THE CATALYST BEING SELECTED FROM THE GROUP CONSISTING OF MIXTURES OF NICKEL, COPPER AND COBALT; COPPER CHROMITE AND SILVER; COPPER AND NICKEL; THE GLYCEROL PLUS ETHYLENE GLYCOL BEING SELECTIVELY PRODUCED AT TEMPERATURES BETWEEN 200 AND 220*C., THE CATALYST BEING SELECTED FROM THE GROUP CONSISTING OF MIXTURES OF COBALT AND NICKEL. 